Multiplexing multimode fiber and Fizeau etalon: a simultaneous measurement scheme of temperature and strain

We propose a sensing scheme to measure temperature and strain simultaneously by multiplexing a section of multimode fiber (MMF) and a Fizeau etalon to construct a novel fiber optic sensor unit. The multimode interference of MMF can monitor the environmental temperature separately without being affected by strain applied on the sensor unit. The Fizeau etalon can measure the strain applied on the sensor unit. The sensor unit is interrogated by a broadband source ASE and its demodulation is performed by an optical spectral analyzer (OSA) combined with fast Fourier transform (FFT) techniques in the spectral domain. A sensor unit is fabricated and tested to prove the feasibility of the sensing scheme